Not all of the fossils in North Hollywood have facelifts and tummy tucks. Just ask the Los Angeles County Metropolitan Transportation Authority (MTA), which earlier this month announced paleontological finds that it made while extending a subway line through Hollywood and into the San Fernando Valley.

During the digging, which began in 1987 and ended last June, researchers recovered more than 2,000 fossil specimens. Their origins span 16.5 million years. The fossils, many representing new spe...